Mystery to be solved - reward to whoever gets it!

[Simoniz]

Re: Mystery to be solved - reward to whoever gets it!

Correct me if Im wrong but isnt the fact that you have solid water flow out of the relief port on one side of the drive and not the other a bit of a red herring?

After the water has run through the manifolds and risers, doesn't it then go into the y pipe where the streams are rejoined before then exhausting into the drive where it then has the choice to exit via the left relief port, right relief port or the prop?

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Hello Simoniz (I can remember as a teen we used to call it "Simonizing" cars instead of "waxing")

Yes you would think that but there must be an exit port before the merge in the Y pipe or something because when I clamp off some on the port manifold supply hose at the tstat housing the stream then switches sides to the starboard side and it cools down real nice ...but the port side then goes up.
I just did this not 15 minutes ago while checking temps.
If it had it's choice of which side to exit why does it change sides when I use the clamp of do a hose swap at the tstat housing?
BTW after engine got up to normal operating temp (165) the temperature on the Elbows was - PORT = 101 / Starboard = 160

This is NOT normal (within 20 degrees yes-normal...59 degrees no something wrong) and NOT a percieved problem on my part.
It is REAL!

Going to do a volume test from the leg next.

There has to be a proper fix for this ... I don't want to rig anything.

Thanks guys

 

[smokeonthewater]

Re: Mystery to be solved - reward to whoever gets it!

when is the last time you changed your impeller

when you put in new risers did you use the correct gaskets? You need a restriction to water flow to equalize flow... Not all gaskets are created equal

PORT = 101 / Starboard = 160

This is NOT normal (within 20 degrees yes-normal...59 degrees no something wrong) and NOT a percieved problem on my part.
It is REAL!

at idle 101/160 is a real difference but a percieved problem

101/375 would be a problem

now the part that gets my attention it that you indicate that this is a progressive issue and as such one could anticipate it becomming a problem over time.

I suspect that your impeller is worn and not pumping as much as it used to at idle and or your riser gaskets aren't restricting water flow as they should

I'd say these two items will straighten you out

 

[JustJason]

Re: Mystery to be solved - reward to whoever gets it!

have a read at this

http://www.boatfix.com/merc/Bullet/99/99_10.pdf

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Well this problem is very real to me as it isn't cooling as it was when I bought it new ...so it is a real problem to me.
Also the impeller and base plate and water seal are new ...that is on my list of things replaced in the first thread.
Also when the maifolds were replaced the full open gaskets were used.
Mercruiser calls for full open gaskets if you have a 3" riser (which I do) in their service bulletin 99-10 (see Jasons post) and that is what I used. Maybe I should go back to the restrictor gasket above the riser and see if that helps? Now that you mention it I can't recall this problem before changing to the full open gaskets on top of the 3" riser. I have some of those gaskets new in my shop also. I wonder why the Mercruiser service bulletin says to change?
That is a good thought though...I may give that a try.

Thanks Jason, yes I am aware of that bulletin and my boat falls into the catagory of #4A

Thanks
Kirk

 

[Fun Times]

Re: Mystery to be solved - reward to whoever gets it!

To find a cutaway diagram of your thermostat housing, Try taking a look in your service manual from mercruiser, (In the cooling section) It may be in there, For example, look at page 6A-53 here in this link below.
http://www.boatfix.com/merc/Servmanl/16/16A6R2.PDF

http://www.boatfix.com/merc/Bullet/93/93_18.pdf

 

[SuperNova]

Re: Mystery to be solved - reward to whoever gets it!

I am confused.......

I assume this is a single engine.......how can you tell the difference in the flow of water from 1 manifold to the other if both manifolds are feeding the y pipe?

I thought the same thing.......

There are 2 outlets at the transom where water comes out right up forward of the drive ... it also comes out through the prop.
Kirk

They access the same plenum at the bottom of the Y-pipe......

Yes you would think that but there must be an exit port before the merge in the Y pipe

No there isn't. The y- pipe horns come together at the bottom of the "y" into a common plenum which then bolts onto the transom plate just ahead of those exhaust ports......

or something because when I clamp off some on the port manifold supply hose at the tstat housing the stream then switches sides to the starboard side

May be more a matter of cyclone effect from more water running down one leg more than the other....but nothing more.

I just did this not 15 minutes ago while checking temps.
If it had it's choice of which side to exit why does it change sides when I use the clamp of do a hose swap at the tstat housing?

Same reason as above......as said before, possible red herring.

BTW after engine got up to normal operating temp (165) the temperature on the Elbows was - PORT = 101 / Starboard = 160

I don't think I'd get excited about this....you may be getting a little anal about temps. If it is all new stuff and it's put together per the T.S.B. and you're not melting hoses........well as said before 300+ on the starboard manifold might be an issue worth investigating, but a manifold running colder than engine temp?.....not worth my time especially if it only does it at idle.......just my opinion of course.

 

[Don S]

Re: Mystery to be solved - reward to whoever gets it!

Also when the maifolds were replaced the full open gaskets were used.
Mercruiser calls for full open gaskets if you have a 3" riser (which I do) in their service bulletin 99-10 (see Jasons post) and that is what I used. Maybe I should go back to the restrictor gasket above the riser and see if that helps?

EDIT: Wrong information removed. :redface:

PS, your 99 shouldn't have any check balls in the thermostat housing at all. That was for older models.

 

[Howard Sterndrive]

Re: Mystery to be solved - reward to whoever gets it!

There's nothing wrong. You are looking for a problem where there is none. What do I win?
who cares what the temps are on the trailer? Shoot the manifolds with a temp gun while on plane.

 

[John_S]

Re: Mystery to be solved - reward to whoever gets it!

Don,

Has it changed from the service bulletin?

4a.
Raw water cooled engines with all the water from the thermostat housing going to the
90-degree fitting on bottom of the exhaust manifold:
Use P/N 27-863726 Gasket ? 4 Slot between the exhaust manifold and the exhaust
elbow.
If the engine has 3 in. (76 mm) or 6 in. (152 mm) risers, use P/N 27-863726 Gasket ?
4 Slot between the riser and the exhaust manifold and exhaust elbow.


I am running the 4 open slot in both locations, and when I first changed them the temp at the top of the elbows seemed slightly lower, compared to having the restrictor gaskets.

 

[John_S]

Re: Mystery to be solved - reward to whoever gets it!

I thought the same thing.......

They access the same plenum at the bottom of the Y-pipe......

No there isn't. The y- pipe horns come together at the bottom of the "y" into a common plenum which then bolts onto the transom plate just ahead of those exhaust ports......

May be more a matter of cyclone effect from more water running down one leg more than the other....but nothing more.

Same reason as above......as said before, possible red herring.

I don't think I'd get excited about this....you may be getting a little anal about temps. If it is all new stuff and it's put together per the T.S.B. and you're not melting hoses........well as said before 300+ on the starboard manifold might be an issue worth investigating, but a manifold running colder than engine temp?.....not worth my time especially if it only does it at idle.......just my opinion of course.

FWIW: When I was messing with mine this spring, running on a tub and water coming out the exhaust reliefs, if you restricted one side of the hose to exhaust, you did see a corresponding difference at the relief ports. It is not 100%, ie some water does come out the other relief, even if you have it blocked off or removed from manifold.

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

"May be more a matter of cyclone effect from more water running down one leg more than the other....but nothing more."
-------------------------------------------------------------------------

Well whats causing it to run more water down one leg is the 64K question.

Look, I am just trying to find out why the sudden -drastic- increase in temps on that side. It shouldn't be that hot.
If you wouldn't worry about it that's great but I like to know if something is developing and don't want to be 15 miles off Cape Fear when I find out..that's all.

Something is causing it to be hogged to the port side ...so what is it?
Thats all I am trying to find out ...if it wouldn't bother you that's fine...but it bothers me because I know that symptoms evolve and then trouble begins.

Don,
I don't know where that diagram came from but my setup falls under the 4A part of the bulletin like I said earlier and it plainly states:

4a.
Raw water cooled engines with all the water from the thermostat housing going to the
90-degree fitting on bottom of the exhaust manifold:
Use P/N 27-863726 Gasket ? 4 Slot between the exhaust manifold and the exhaust elbow.If the engine has 3 in. (76 mm) or 6 in. (152 mm) risers, use P/N 27-863726 Gasket ? 4 Slot between the riser and the exhaust manifold and exhaust elbow.

I wonder why they changed the setup anyway?

If I try the restrictor gasket then it will be between the riser and the elbow which is where mine were when new. When new the 4 slot open gaskets on mine were between the manifold and the riser.
Thats why that diagram looked odd to me.

And for Howard and Nova - yes same thing on plane ...big difference. Like I have stated before this occurs on the trailer AND on plane.
Not just at idle.

Thanks anyway guys ...I will figure out what is causing it.
You guys have been great ...thanks again.

Kirk

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

"No there isn't. The y- pipe horns come together at the bottom of the "y" into a common plenum which then bolts onto the transom plate just ahead of those exhaust ports......"


The exhaust gas goes out the upper portion through the big outlet.
The water is held (mostly) to the lower portion of the pipe by gravity and mostly exits through the two ports at the transom.
Therefore there is a direct connection as to how much water is comming down each leg versus how much is comming out of each of the two exit ports on the side of the transome plate. See pic.

It all doesn't just merge at the Y point. I don't think it is a cyclone
effect.
Y pipe 4 pic is, of course, upside down.

This is how I know there isn't enough water comming through the starboard side... it just spit/sputters out that port.
Port side full flow.
Had just about equal flow out both holes when new.

This is how I know something is/is going wrong.

Kirk

 

[Fun Times]

Re: Mystery to be solved - reward to whoever gets it!

[QUOTE=Simoniz;2861337]Correct me if Im wrong but isnt the fact that you have solid water flow out of the relief port on one side of the drive and not the other a bit of a red herring?

After the water has run through the manifolds and risers, doesn't it then go into the y pipe where the streams are rejoined before then exhausting into the drive where it then has the choice to exit via the left relief port, right relief port or the prop?[/QUOTE]

I am confused.......

I assume this is a single engine.......how can you tell the difference in the flow of water from 1 manifold to the other if both manifolds are feeding the y pipe?

I thought the same thing.......

They access the same plenum at the bottom of the Y-pipe......

No there isn't. The y- pipe horns come together at the bottom of the "y" into a common plenum which then bolts onto the transom plate just ahead of those exhaust ports......

May be more a matter of cyclone effect from more water running down one leg more than the other....but nothing more.

FWIW: When I was messing with mine this spring, running on a tub and water coming out the exhaust reliefs, if you restricted one side of the hose to exhaust, you did see a corresponding difference at the relief ports. It is not 100%, ie some water does come out the other relief, even if you have it blocked off or removed from manifold.

This is because the the transom assembly has three holes to exit the water out, coming from the controlled Y pipe.

See the photo on page 7D-2 here in this link, It should be able to help you see and understand how the water flows out. Hope this helps.

http://www.boatfix.com/merc/Servmanl/16/16D7R2.PDF

 

[smokeonthewater]

Re: Mystery to be solved - reward to whoever gets it!

well we now have a real good idea that the source of your issue is the gaskets..... SOOOOOOOOO get em swapped out and I'll give you an address for my prize

 

[Black as]

Re: Mystery to be solved - reward to whoever gets it!

I would remove the thermostat and run your engine in the lake and then check your temperatures of each manifolds just to see if anything has changed.

 

[JustJason]

Re: Mystery to be solved - reward to whoever gets it!

I would remove the thermostat and run your engine in the lake and then check your temperatures of each manifolds just to see if anything has changed.

That's about the worst advice ever.... Beside, exhaust coolant is indepentant of, and doesn't rely on a tstat to regulate it's temp.

 

[KWG]

Re: Mystery to be solved - reward to whoever gets it!

Yes I agree with you Jason
The Y pipe is controlled ...each side comes out on its own side at the transom and the exhaust gases mix and come out throught the big hole in the middle through the prop. (along with some water that gets mixed into the gases on the way down the pipe. Majority of the water is in the bottom of the pipe and goes out it's respective side. I proved this to myself by removing the supply hose to the port side and blocking the outlet at the tsat....the port outlet hole on the transom completely stopped and it went full flow out the starboard side...that proves they are seperate. There is no vortec effect.
I posted 3 pics. (I can't get the boatfix images to load)

I will keep searching and probably try those restrictor gaskets just to see if that is it. I will let you guys know what happens.

Thanks
Kirk

 

[John_S]

Re: Mystery to be solved - reward to whoever gets it!

Unless you put a restricter gasket instead of a 4 slot, but would explain why it moves with swap of hoses.

Lets go back to your experiment where you close off the port side, then release it, and the flow stays good on both sides. This stays like that until you shut the engine down for some time? Outside of some form of airlock, that goes away once you force enough flow to one side? Have you tried just restricting the port side hose slightly with a hose clamp etc, but not closing it all the way off?

 

[Don S]

Re: Mystery to be solved - reward to whoever gets it!

Don,

Has it changed from the service bulletin?

No, it didn't change. Looks like I was reading 4B instead of 4A. All gaskets should be 4 slotted gaskets in his setup.

Sorry.

Will edit my posts so as not to confuse things.:redface: :redface: